1. Field
The present technique relates to a controller or the like which controls movement of a head mounted to a storage apparatus based on a signal output from an acceleration sensor.
2. Description of Related Art
In recent years, magnetic disc apparatuses are being miniaturized and light-weighted, and thus the magnetic disc apparatuses are mounted also to terminal devices (notebook computer or the like) which can be carried by users. However, since magnetic disc apparatuses are used for recording/reproducing data by means of moving of a head onto a rotating disc, they have a disadvantage in that they are weak against external impact. That is, when a magnetic disc apparatus receives impact or the like that causes a drop at the time of recording/reproducing data, its head comes in contact with a disc so that the disc is damaged. In the worst case, data recorded on the disc cannot be reproduced. The impact can happen, for example, if someone trips over the power cord, pulling the apparatus off of a table. In that example, the impact causes a drop to the floor, resulting in a second impact on the floor. This technique focuses on the first impact.
Therefore, in order to solve the problem that data recorded in a disc cannot be reproduced due to impact or the like resulting in a drop, conventionally a drop sensor is mounted in a magnetic disc device. In the case where a drop of a magnetic disc apparatus is detected (drop time exceeds a threshold), the head is unloaded from the disc. Such a head unload control is disclosed in, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 2002-208239, 2004-146036 and 2005-190641.
However, in the above conventional technique, a head is unloaded from a disc based on the drop time starting from actual drop; therefore when a drop distance is short, a magnetic disc apparatus receives impact caused by the drop before a drop condition is satisfied. As a result, the head and the disc are damaged, and data stored in the disc cannot be protected.